a3a2bd9e8a ci: Drop no longer needed package-specific flags (Hennadii Stepanov)
071eef1e97 build: Propagate user-defined flags to host packages (Hennadii Stepanov)
Pull request description:
On master (4f8b1f8759) `{CPP,C,CXX,LD}FLAGS` that are specified in the command line are not propagated to packages:
```
$ make --no-print-directory -C depends print-libevent_cxxflags CXXFLAGS=-some-fancy-flag
libevent_cxxflags=-pipe -O2
```
This PR:
- propagates `{CPP,C,CXX,LD}FLAGS` to host packages:
```
$ make --no-print-directory -C depends print-libevent_cxxflags CXXFLAGS=-some-fancy-flag
libevent_cxxflags= -some-fancy-flag
```
- does not propagate `{CPP,C,CXX,LD}FLAGS` to native packages:
```
$ make --no-print-directory -C depends print-native_b2_cxxflags CXXFLAGS=-some-fancy-flag
native_b2_cxxflags=
```
- actually addresses the https://github.com/bitcoin/bitcoin/pull/23551#issuecomment-973896518
ACKs for top commit:
TheCharlatan:
Code review ACK a3a2bd9e8a
Tree-SHA512: 243d6b1b0e9c5de46debc36de62a77b6b4d6f638940fd530040c219956ec624e321b0c25290fed164e3a8c88befa7b97b20f765d7b9a428c269b3720f21da099
